Endless traction belt



' March 20, 1945. F. w:' CHRISWELLI ET'AL ,3

ENDLESS TRACTION BELT Filed May 20, 1943 2 Sheets-Sheet 1 I 3mm FREOERIOK (dcuaiswccc. mo

Match 20, 1945'. WCHRISWEJLL ETAL 2,371,802

ENDLESS TRACTION BELT Filed May 20, 1945 2 Sheets-Sheet 2 Rbaea'r 5 (.nnzbon Patented Mar. 20, 1945 y,rr er srmwfl re w Frederick Ghriswell andiRobert: ismgdon I Seattle, Wash.

, 11 Claims. This. invention relates. to an. endlesstra'c'tion belt. composed-of padsor shoes hinged at their edges, with rail members for load carryingwheels and, means to .truss the, pads, and. preventlthem 1 from. buckling inward, such means composed of aprojecting arm terminating in a hook to engage astirrup which is anchored at the hinge pin. The stirrup. is pivoted. 0n the hinge. pin of one pair. of pads and. engages the hook..membe r of the adjacent pad.

I'he primary purpose of this invention. isto.

I construct endless track linkage to form track lay-e ing whee1 substitutes capable of convenientfield repair without the useof. special tools and, equip,- ment', H t

. Ont-of the objects of this invention istoiorm alink-shoe: and. truss-arm. construction by cast-T ing, so; that this assembly can bev properly hard-= ened to resist wear, .and,.to utilize with this unit a rorged stirrup of a softer metal to permit .fajster wear of this part, for convenient. and inexpensive, replacement. As an example the; casting may be or carcometalp heat treated to suitable hard ness, while thestirrup and hinge pin therefor: are

, drop-forged. An S-. A.,.E. 1040 maybeyindicated 42: further, object of the present invention isto so; locate the: stirrup that the stress developed in.- the truss is lower than :in conventional qassem bliesthus reducing materially the wear -on,-.this, member. l 1

.More specifically, this invention contemplates; the; use of a tread link unit comprising a pad, on shoe and integral truss armand hook, and a stir-.: rup hinged thereto, the-hook with its curved outer responding. parts throughout the "several views. in which;

Fig. .1 is a side elevationof a track laying I link Fig. Z'isa side elevation oiatrack section-with the, padsin relative positionbefore the parts are:

worn.

movedjto fullbent position.. l

Fig, 4is atop plan ofatracksectiom H ."Eig. 5 isan end elevation of a link showing tlie stirruphinge. f

,Fig. 6 isa longitudinal section of lin'e\6 6' or, Fig.4,and Fig, 7. is, y a bottom plan nectedlinksft a 1 Referring, particularly, to Fig; 1, there is illustrated a track laying. assembly to, which the wheels Af'B maybe of conventional design and,

view of a pair, or 1 con therefore, are a merely illustrated: diagrammatically. The present construction is. such that it i may 'b'', adaptedto any standard running gear and, consequently, is suitable for'either original installation or replacement in other equipment.

IniFig. 1' it will ice-apparent that the units are so constructed and dimensionedjthat the track stretches embody a camber. The groundline Cand the ground stretch D showing this feature,

the details of which will more clearly herein after appear by. a detailed examination of the individual link assemblies.

[ The linlgassemblies eachcomprehend a tracextremity engaging the curved. free'endof the adg'iacent stirrup to provide the essential freedom of'movementso as toadjustitself and, thus elim inate expensive machining of any kind; .at ;the1 wear point. Both the pad or shoe, with. itsin-i tegral hook, and the stirrup will. be soudimeni- I tive'ly.

sione'd as: to incorporate; a camber in a the. new

assembled belt. Use of the belt will. eventually eliminate the camber due to-wearofgthe working facesguntil the: belt will be substantially fiat, or a slight reverse camber :is formed: When this occurs, replacement of'the stirrupswill return the. belt to its original "camber,"minus the wear IBy the foregoing constructions, the spec'ified objectsamong others will be accomplished. Other objects will hereinafter appear by reference to" tion [pad or shoe ljformed'with wheel carrying" raidlsurfaces 2 and forwardly and rearwardlyx extending pairs of spaced lugs 3 and 4, respec- Ihe forward'lugsil are relatively spaced to receive between them the rearwardly extending spaced lug 4-of thenext adjacentlink and each flug is formed with a transverse opening so.

formed-and arranged that all openings will be aiigned in assembly to permit the insertion of a hinge pin 5"asis usual in such constructions. n wm be-noted that the forward lugs} extend laterally from the side walls 6 of the-shoe l and underlie the rail "portions 2 adjacent the ends thereof. These lugs3 and the-depending flanges 'l which reinforce the forward end of the ran 7 portions 2" tend to strengthen the assembly and iiaccompanying drawings and "speciiicatii m 1 wherein dike rererencezcl-iaracters designate cer form the essential bearing structure forthe extrernitiesof the hinge pins 5. The rear lugs 4 are -so-=spaced' that their outer faces twill-engage snuglybetween the inner races 9 of the forward wheel and running gear embodying my invention and 1 illustrating the beams formed by a the stretches.

Fig. 3 is a similar viewwithone ofthe lin'ks are formed with inwardly extending-angularly arranged shoulders I! which act as limit stops for defining the outward movement of the stiry rup l2 while the lateral guiding action is prostirrup is confined. Outwardly of the shoulders I! the walls I4 merge into the hooked extremity of the stirrup l2, which end portion is constructed to absorb a maximum portion of they wear as between these parts.

, The stirrup's 12 are preferably'drop-forged'to provide a relatively elongated body terminating at one end in the eyelets II and at the other endin the rounded, relatively thickened outer end portion l8 which as'stated is designed to engage the curved socket I9 formed in the outer end portion of the curved hook of the truss member. By this constructionthe workingfaces between the hooked truss member and the free end 18 of the loop or stirrup are .curved tojprovide necessary freedom of movement sothat these parts will be self-adjusting and'so that the desired relative movement between the parts may be, obtained without amachining operation. The shoe or pad I; with the rail members for the load carrying walls, and the truss member, including the hook, are cast as a unit, this unit likewise embodying the lugs formed with the 'pin receiving openings. The casting is preferably made of a metal which may be heat treated to secure desirable'hardness while the stirrup l is drop-forged and therefor relatively soft. By

this construction it will be apparent that the wear will be essentiall' ion the drop-forged niemher, which member is readily replaceable by the simple expedient of; removing the hinge pin.

Thus, .the life of the cast unit is materially.

lengthened and the use of essential materials eliminated.

In the construction of the parts ta, the. cast-.

ing and the stirrup it is intended that there be sufficient freedom of movement so that the necessary seating between thefstirrup and the truss will be accomplished. The clearances and dimensions between the casting and the stirrupare such that when the link belt a is originally assembled, a camber is formed inthebelt, this camber becoming less as thestirrup isworn at its point of engagement with the hook until the belt is relatively flat or the camber is slightly in which obviously is extremely unsatisfactory under many working conditions.

. In this type the, track pad has two'arms spaced fore and aft,

which constitute the parts that form the truss, one arm terminates in a hook and the other in an eye to receive a pin. The hook oi one pad engages the pin of the adjacent pad. preventing the hinge from further movement and thus form- .ing the truss. To prevent the wear coming all on one place of the pin, it is loose and allowed to float. The arm with the eye is bifurcated and the two parts are spaced apart and a bushing is placed on the pin and shrunk on to, prevent the endwise movement of the pin. To remove the pin for repair, a torch is required to heat the bu'shing and expand it to loosen the pin. On vided by the walls themselves, between which the account of the hook engaging a pin, exact machining is imperative to secure the required con- 1 tact surface and'distribute the stress and wear equally. Any misalignment of parts would be a detrimental. The fact that there are two hooks to contact the ends of the truss pin, any unequal v In one type field repair is practically impossible without specialtools and equipment mentsincludinga wall portion adjacent said shoe 76,

wear would complicate replacements, as the two hooks must contact the pin at the same time.

The other conventional design is such that high stresses are developed in the links and hooklinks that form the truss which necessitates the use of alloys essential to the war industry, and also demands an exact technique in manufacture. The hook-links have tapered shanks where they enter the pad' and this taper should be polished to remove tool marks and thus forestall'early fatigue which is common to taper fits. When new wheels are put into service the nuts on the hook-links should be frequently tightened until properly seated. A specialsocket necessary to reach the nuts.

' The present invention eliminates these obiections and provides an assembly in whichfield repair can be made and perhaps whatis more important the wear is primarily confined to a single inexpensive elementwhich is constructed and arranged for quick replacement.

' In use itwill be'obviou's to one skilled in the art that due to the method of manufacture'the wear will mostly be at the outer end of the stirrup, which incidentally is formed relatively thicker at'this point so that at all times it will possess the necessary strength. When the stirrup is so worn at this point that the camber is substantially eliminated or reversed, then by simply removing the hinge pin anew stirrup may be included in'theassembly. This will inherently return the "camber except for-that minimum amount represented by the wear of the hardened hooked truss. By this means a substantially greater use of a tread unit is possible without the loss of desirable features, and expense and loss I of time is kept at a'minimum.

'What I claim is: 1. In atread linkage, a pair of links having shoe parts, hinge'means connecting said parts for relative co-axial movement, said links having truss forming elements upstanding from said shoe parts when the latter are in ground engaging position. said truss elements including spaced walls and an extremity defining a'hook, and means pivotally mounted on the hinge means forv engaging the hooked portion of the truss of the adjacent shoe.

s 2. Ina tread linkage, a pairlof links having shoe parts, hinge means includinga hinge pin connecting said parts for relative co-axial movement, said links having truss forming elements upstanding from said shoe parts when the latter are in ground engaging position, said truss elean a extremity, d fi ing cancer, and stirrup wrench is means pivotally mounted on the hinge means for engaging the hook of the truss-of the adjacent shoe.

3. In a tread linkage, a pair of links having shoe parts, hinge means connecting said parts for relative movement, said links each having truss forming elements upstanding from said shoe parts when the latter are in ground engaging position, said truss elements each including spaced wall portions and an extremity formed with a hook portion, and an element pivoted to said hinge means and extending between the spaced walls of the adjacent truss element for engaging the hooked portion of the truss element of the adjacent shoe for transmitting truss forming stresses between links. l p

4. In a tread linkage, a pair of links having shoe parts, hinge means including a removable pin connecting said parts for relative movement,

said links each having truss forming elements upstanding from said shoe parts when the latter are in ground engaging position, said truss elements each including spaced wall portions and an extremity formed with a hook portion, and a stirrup pivotally mounted on said hinge pin and extending between the spaced walls of the adjacent truss element for engaging the hooked portionof the truss element of the adjacent shoe for transmitting truss forming stresses between links.

5. In a tread linkage, apair of links having shoe parts, hinge means connecting said parts for relative movement, said links each having truss forming elements upstanding from said shoe parts when the latter are in ground engaging position, said truss elements'each including spacedwall portions and an extremity formed with a hook portion, an element pivoted to said hinge means and extending between the spaced walls of the adjacent truss element'for engaging the hooked portion of the truss element of 'oted element to limit its outward hinged movement.

'7. A tread linkage comprising hinged shoe members each having truss extension to prevent inward bending, said tread members and trusses being formed of hardened material and said trusses each including a. curved bearing portion and a removablehinged stirrup formed of relatively softer material for connecting said hinges and truss bearing portions for transmitting truss forming stresses, whereby the wear willaccumulate at the removable part.

8. In a tread linkage of the class described, a

pair of links each having shoe parts and truss iorming parts, said truss forming part including a bearing portion of hardened material, hinge means connecting said links, and removable stirrup means pivoted on said hinge means, said stirrup means being formed of relatively softer material than said bearing portion and engaging the adjacent truss ior'guided movement and the truss of the adjacent link at its bearing portion for transmission of truss forming stresses between links, whereby said stirrup may be replaced upon accumulation of excessivewear.

9, A vehicle track chain formed of a plurality of shoes, each comprising a tread member hav-- ing hinge lugs projecting from the opposite sides thereof, pintles for pivotally connecting the hinge lugs of adjacent shoes, means for trussing said shoes including integral extensions extending 1117-, wardly and rearwardly when said trackchain is in ground engaging position of said-truss, means including spaced walls formed with inwardly projecting shoulders, and said walls merging to form an extremity having a hook shaped portion,

the adjacent shoe for transmitting truss forming stresses between links, and means for limiting the hinge movement of said pivoted element.

6. In a tread linkage, a pair or linkshaving shoe parts, hinge means including a removable pin connecting said parts for relative movement, said links each having truss forming elements upstanding from said shoe parts when the latter are in ground engaging position, said truss elements each including spaced wall portions and an extremity formed with a hook portion, an element pivoted to said hinge pin and extending between the spaced walls of the adjacent truss element of the adjacent shoe for transmitting truss forming stresses between links, and shoulders projecting from said walls for engaging said piv-,

and stirrup means mounted on the hinge pin of one pair of shoes and extending between the walls of the adjacent truss means; and engaging the hook shaped portion of the adjacent shoe,

said stirrup being limited in its movement by the shoulder of.the adjacent truss means.

10. The structure setforth by claim 9 further characterized in that the engaging faces between the stirrup and truss are respectively convex and concave shaped to insure relative'movement and adjustment. 11. A vehicle track chain formed of a plurality of cast units each including a tread member, hinge lugs'at opposite sides, and a truss means terminating in a hook shaped portion, said unit being hardened to be wear resisting, hinge pins connecting said units, and a removable stirrup pivoted on the hinge pin of one unit and engaging the hooked portion of the adjacent truss, said stirrup being formed of relatively soft material.

FREDERICK W. CHRISWELL. ROBERTS. LANGDON. 

